This study examined the impact of a systemic reform initiative to implement standards-based mathematics and science teaching and learning in one urban school district, noting its effect on teachers, principals, students, and classroom practice. Participants were a sample of elementary and secondary schools involved in the Milwaukee Urban Systemic Initiative (MUSI). Researchers collected data via interviews with principals, teachers, and students and observations of mathematics and science instruction, emphasizing: the MUSI's impact; whether teaching was standards-based; opportunities for teacher collaboration; and leadership for mathematics and science. Most elementary and middle school teachers felt the MUSI had a great impact, but high school teachers saw little use for it. Teachers wanted more collaboration time, stronger leadership, and continuation of the MUSI. Movement toward becoming a community of learners was apparent in some schools. Principals recognized the need for multiple methods of teaching and for keeping teachers current regarding instructional materials. Principals also acknowledged the need for teacher collaboration but mentioned lack of time during school days. Leadership varied across schools. Students reported enjoying mathematics and science more and applying themselves more when challenged. Observations of classroom practice showed that much instruction was not standards-based, though at all levels in both disciplines there were some strong examples of it. (SM)